A series of vinylene-linked copolymers based on electron-deficient benzobisthiazole and electron-rich fluorene moieties were synthesized via Horner-Wadsworth-Emmons polymerization. Three different polymers P1, P2, and P3, were prepared bearing octyl, 3,7-dimethyloctyl, and 2-(2-ethoxy)ethoxyethyl side chains, respectively. The polymers all possessed moderate molecular weights, good solubility in aprotic organic solvents, and high fluorescence quantum efficiencies in dilute solutions. P2, which bore branched 3,7-dimethyloctyl side chains, exhibited better solubility than the other polymers, but also exhibited the lowest thermal decomposition temperature of all polymers. Overall, the impact of the side chains on the polymers optical properties in solution was negligible as all three polymers gave similar absorption and emission spectra in both solution and film. Guest-host light-emitting diodes using dilute blends of the polymers in a poly(N-vinylcarbazole) host gave blue-green emission with P2 exhibiting the highest luminous efficiency, 0.61 Cd/A at similar to 500 nm. (C) 2012 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 916-923